How to ground work in a lathe?

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What do you all use to ground the welding work in a lathe? Anyone made a rotary ground of some sorts? I never ground the whole lathe, the bearings would become lumpy.6"XX P5P8 6G
Reply:Definately NOT a good idea!!!!If you plan on doing welding with a lathe, you better have an old piece of $hit set up for this. You will destroy the machine in many ways.Go buy an old clapped out machine with bad ways and bearing and use that.http://jackalopefab.com/MM210Synchrowave 200DXMiller XMT350 w/60series feederMiller Bobcat 250 with SGA 100 and spoolgunHTP PlasmaFull Machine shop with everything
Reply:I fix stuff in my lathe occasionally when it's too much of a pain in the rear to take it out and set it up again..But it is also Tig so there are no sparks or slag...Ground goes on a chuck jaw  and all is good..The ground has nothing to do with the bearings that way..Don't ground the bed..Then the bearings take a beating....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:how are you going to ground the chuck it spins?
Reply:Hello Cofe, I have used the brushes out of large engine driven welders and made a spring loaded mount to hold them against the part that is being rotated. I would concur with the other suggestions to utilize an old worn out lathe if I had to do a lot of this sort of work and would also be very careful about protecting the ways and other delicate surfaces and bearings. Whenever you are doing welding that requires rotation while the work is being performed it is obviously going to be a pain in the arse. If it is only a matter of a single rotation of the part I would agree with wrapping the ground cable around the chuck/part and attaching the clamp to the chuck jaw, if wrapped properly the cable would unwind as the part is being rotated and not foul anything up. If the welding involves many turns(such as doing a rotary build-up of a shaft or something) then the brush suggestion that I included above might work. If using the brush type set-up could cause arcing on the part then you might have to include a seperate ring that could be clamped around or otherwise attached to provide a good tight ground and a sacrificial surface for the arcing from the brush to take place on. Just a few additional thoughts for your consideration. Best regards, Allanaevald
Reply:Originally Posted by CheneyKidhow are you going to ground the chuck it spins?
Reply:Hey I appreciate all the information. I am a bit skittish about welding in my lathe, and it makes sense to ground the chuck and turn it by hand. I also liked the brush idea for building up shafts. I will be looking for a old/junk-o to try that out though. I have used roto grounds welding tanks on rubber rolls. But I didn't want to justify the expense of one of those. Attached Images6"XX P5P8 6G
Reply:I don't care who on here does it, it is a BAD idea. If you think I am just being stupid, please call any machine tool user and ask them. Better yet, call a lathe company and ask them how to safely do so it will not damage any part of the machine. They will tell you that you cannot.If you don't care about your tools, go for it. Very stupid to do with a good machine.Granthttp://jackalopefab.com/MM210Synchrowave 200DXMiller XMT350 w/60series feederMiller Bobcat 250 with SGA 100 and spoolgunHTP PlasmaFull Machine shop with everything
Reply:When I worked in a job shop welding on a chucked part was a sometimes a necessary evil. Most times these parts were big, odd, and ugly. Not to mention it may only require one pass be welded to bring the part in. Grounding to the chuck jaw as zap said is good. On solid parts (shafts etc.) tacking a piece of round bar close center on the face of the face of the work and hanging the ground clamp over it is affective. That is if the face isn't already finished and critical. Welding in a lathe isn't something I would do on a regular basis but sometimes the setup time just doesnt justify not doing it. Unless, as has been said, you intend to use said lathe as a full-time welding lathe. I've run 3 different weldlathes 2 made by Bancroft, the other was custom built on an ancient Monarch engine lathe bed. Those machines used rotary grounds through the spindle shaft. Cover the ways with a blanket or piece of wood to keep the spatter and slag off.Ranger 250 GXTSmith Gas Axe
Reply:Originally Posted by jackalopeI don't care who on here does it, it is a BAD idea. If you think I am just being stupid, please call any machine tool user and ask them. Better yet, call a lathe company and ask them how to safely do so it will not damage any part of the machine. They will tell you that you cannot.If you don't care about your tools, go for it. Very stupid to do with a good machine.Grant
Reply:Hello Zap, you did remind me of something that, in a remote instance, could be an issue. If for some reason the ground clamp/cable unit didn't make proper contact with the part and the electrical ground of the welder was common to it's own electrical ground and shared the electrical ground with the lathe, you would in fact end up with a serious issue and possible arcing that could damage parts of the lathe. That scenario is one that generally supports the use of isolator hooks on bridge cranes and reinforces the lack of welding on suspended parts from cranes without isolation. Certainly something to consider. Best regards, Allanaevald
Reply:Last time I will comment at all. Don't do it. Bad idea. I don't care if others have done it. I think this is why machinist don't always like weldors. Careless and no regard for good machine tools.I am not saying anyone here is that, but these comments certainly lead me to the conclusion I would NEVER buy a machine tool from anyone claiming to do this sort of thing.Bad practice no matter how you slice it.Buy a dedicated welding lathe and destroy it. Or better yet, make a positioning fixture specific to this application.Do it right. I always think "should I do this." When I have to ask myself that question, the answer is a resounding, "NO!!!!"Not to be a d!ck, but this would be a great learning lesson for you to go ahead and do it and ruin the machine. It is something you would remember forever.Granthttp://jackalopefab.com/MM210Synchrowave 200DXMiller XMT350 w/60series feederMiller Bobcat 250 with SGA 100 and spoolgunHTP PlasmaFull Machine shop with everything
Reply:Originally Posted by jackalope. . . Bad practice no matter how you slice it.Buy a dedicated welding lathe and destroy it. Or better yet, make a positioning fixture specific to this application. . . .
Reply:Originally Posted by jackalope I think this is why machinist don't always like weldors. Careless and no regard for good machine tools.Grant
Reply:Originally Posted by zapsterI happen to be both.Maybe that's why I don't like myself..My lathe has tried to kill me twice...Don't mean I have to kill it.I have been doing these repairs for 30 years..Done RIGHT there are no issues..Just ask my lathe....zap!
Reply:I have welded parts on lathes,on bridgeports, edm and cnc machines proper ground and all is good
Reply:Originally Posted by denrepOkay, but where do we send the bill for the extra machine(s) and set-up time? Jackalope - Posters have given very good examples of welding  lathe-held parts, and specific methods they have used to successfully accomplish same.Meanwhile, you're screaming "no" and "bad" and promising lathe destruction and doom, without giving any specifics. How about detailing what you believe is so wrong with lathe-welding, when taking the precautions that Aevold, Cofe, MrLeadMan, and Zapster have described?Good Luck
Reply:Originally Posted by welderman1I have welded parts on lathes,on bridgeports, edm and cnc machines proper ground and all is good
Reply:Originally Posted by jackalopeI would fire you instantly if I came in my shop and saw you do ANY of the above! Your actions are a very good reason many machinists don't have a high regard for weldors. They see them as careless. This certainly fits the stereotype. I do not believe all weldors are careless and know very many that are certainly skilled and meticulous. Grant
Reply:I realize that there are applications that MUST be welded in a lathe. I am not arguing that point. What I am trying to say is that you do not use a GOOD machine tool to do it in. For cryin' out loud. I could care less what anyone does with their tools, but it is bad practice and it only takes one time.This is why I said you get an old clapped out machine that does not matter. You simply do not do this to a good machine tool.I believe I have beaten this proverbial "horse to death" and at this point don't care what anyone does with their tools. I will refrain from any further comments this time.http://jackalopefab.com/MM210Synchrowave 200DXMiller XMT350 w/60series feederMiller Bobcat 250 with SGA 100 and spoolgunHTP PlasmaFull Machine shop with everything
Reply:I saw the horse twitch, gotta finish 'em off. I never welded anything up in a tool room lathe, those parts are small enough to be a none issue. The parts I've welded up were in a 24" Clausing Colchester and a 40" Monarch with a 28' bed. Parts were proportional to the machine sizes. As I said big ,odd, and ugly.Ranger 250 GXTSmith Gas Axe
Reply:Originally Posted by jackalopeI would fire you instantly if I came in my shop and saw you do ANY of the above! Your actions are a very good reason many machinists don't have a high regard for weldors. They see them as careless. This certainly fits the stereotype. I do not believe all weldors are careless and know very many that are certainly skilled and meticulous. Grant
Reply:....If you have to weld there......ground with rotary on the chuck.....or I've used BIG copper/brass hook hanging on the work/shaft....shouldn't be a problem....you won't be turning more than a couple or 3 RPM...eh?   I've done a couple dozen big 304 stainless augers like this....4-6" shaft, 18-24" diameter flights on 8" sch. 40 pipe........18-30 feet long....200-300 amps TIG...run about 2-3, maybe 4, RPM... for welding at the  base of flights.....end to end...maybe 30-35 revolutions....  Worked fine....food grade stuff too....have to have some pretty smooth welds......Agricultural/food inspectors like it to look like a machine applied bead of sealer....no dime stacking allowed....Dougspair
Reply:....Yes, after reading some of these prior posts....do not ever even consider welding through a bearing......old motorcycles had neck bearings etched away just from the small return current/voltage going to the headlights, 6-12 volts....<10 amps...they are all connected with wiring now days....Dougspair
Reply:The closer the ground to the piece in this application the better.My boss would fire me for not doing repairs in a machine..When he himself is running it.The big lathe is a MAJOR pain in the *** to set up so shrinking of sleeves and welding of said sleeves are done in the machine. (I don't run that one)Leave the roller on the steady rest and do the shrink...Let cool in place.After cooled to where I like it then insert center back off the steady rest and weld the shoulder then the end..Stuff in the big machine is all stick welded.Cover up the ways and have at it.The shop has been doing this on that particular machine since 1958And it still works just fine.Welding in a machine is no big deal if done CORRECTLY....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.If you weld a workpiece while it is in a lathe and and youre ground wire isn't grounding very good and the welder sorta notices that the welding machine sorta goes from hot to cold while welding, it's because the current is going through the spindle or center bearings, and that is tuff on the bearings (not to mention expensive to fix, especially if it's the spindle bearings).  Anyway the lathe is grounded to the same ground that welder machine is grounded.  One way out of that dilemma is to use a engine powered welding machine.  That way, if you loose your ground, or if you have a poor ground connection, you stop welding!  At least you cannot ground through the lathe in any way since the lathe and the welding machine are on 2 independent circuts that are completely isolated from each other. Does this, or am I making any sense?  Or does everybody understand what I mean?  That when using an engine powered welder that you cannot ground through the lathe, or whatever kind of machine tool that you are welding in.  And then if you cover everything up to prevent splatter from sticking then I cannot see any reason why you could not weld up a workpiece while in a machine. Just had to say that,   Doggie    Last edited by Doggie; 10-20-2009 at 01:40 AM.
Reply:But Doggie, Isn't about any welding machine's work circuit separate and isolated from the supply circuit's ground connection anyway?Woof woof
Reply:So like here is what happened in our shop, twice.  First the welders are grounded to the building so ya can go anywhere and only use one lead and a short ground to nearest building frame. Sounds good but not at all a good idea. Reason being our lathes run on 460 3 phase with an equipment ground. Nice and safe. Until ya hook up a faulty welding ground clamp to work chucked in the lathe. Start welding and the current returns to the welder via the lathe ground and not the welder ground. Intense current through the ground wire burns through the insulation of the other 3 460 wires resulting in very loud noises, some smoke and subsequent loss of power. This was caused by a loose connection on the ground clamp and wire connection and the welders work connection connected to the the building frame. Its no fun pulling 4 wires around the shop perimeter inside the conduit cause of this. I have since removed the building ground connection as all those guys have moved on so what I use from the welder can only return to the welder, no sneaky paths allowed. Additionally protect the lathe from hot stuff with leathers and don't weld through bearings. Me? I don't weld on our lathes unless the lathe is broken and needing welding itself. You? Do what ya want.
Reply:Fred Paul Jones - But wouldn't that same scenario be possible even without a lathe?For example, what if a grounded power tool, or maybe a drop light,  was in contact with the work?Good Luck
Reply:Wow Denrep   I never thought of it, that the welder's transformer output (and leads) would have to be isolated from the building(s), and the welding machine(s) input wire ground. Now that I have thought about it, it would have to be that way or you would never be able to switch polarities on the leads would you? So answer me this. When you touch the hot (or positive) lead only and the machine, welding machine, building, or whatever that is grounded. It will shock you, I have found that out by experence. and that can happen whether the welder(s) other lead is hooked up or not. My opinion is that if you can get shocked then you can also ground through the spindle / or center in the tailstock.  That is why I suggest to use a engine powered welding machine, as they will be both completely isolated from each other.Your friend, Doggie
Reply:Doggie you still aint 'splained to me what you mean about this isolation stuff.Ranger 250 GXTSmith Gas Axe
Reply:I think he is saying he has seen leakage between the primary and secondary circuit of the transformer, so by using a gas run welder, there is no primary which plugs into the building (or is grounded to it) and thus the fault can't exist.
Reply:Ok, here's an idea....How about claimpin the ground to the end of the work somewhere out of the way and tack welding the work so that it is true then finishing the work on a table where you can roll it as fast/slow as needed?
Reply:OK, Here goes. A welder would have to have it's transformer secondary (output leads) electricitly isolated and insulated from the welder cabnet, building beams, machinery, ETC. It would have to be that way,- or- You would not be able to switch the + & - polarities. Or if you decided to switch to negative electrode and positive ground, or vice-versa, then the fireworks would start if either of the welders output leads were grounded. UNLESS the polarity switch had several sets of contacts that would take care of that. I have never paid any attention to that the way that switch was wired????? ALL I KNOW is that if you grab the positive lead and touch any ground, even without the other lead being hooked up, and you get a good connection------youre gonna get a thrill.  This is why I say to use an engine powered welder, because if it is not touching the machine youre welding on (or in) you cannot get shocked, and there cannot be any electricity going through any spindle bearings / or ways of the machine tool.Thats all. Your friend, Doggie
Reply:Originally Posted by Doggie. . .ALL I KNOW is that if you grab the positive lead and touch any ground, even without the other lead being hooked up, and you get a good connection------youre gonna get a thrill.   . . .
Reply:Nope. Never got a buzz holding lead and touching something grounded. Still dont get the idear!Ranger 250 GXTSmith Gas Axe
Reply:WOW this is sounding like an OFF TOPIC post. Lets weld the damned thing and go get a bier.
Reply:Here is what you need.http://www.practicalmachinist.com/vb...er-190825.htmlhttp://jackalopefab.com/MM210Synchrowave 200DXMiller XMT350 w/60series feederMiller Bobcat 250 with SGA 100 and spoolgunHTP PlasmaFull Machine shop with everything
Reply:There is the issue of justified output of cash. You need enough work to justify a dedicated machine. In a job shop.... Oh why am I even trying you just don't get it.Ranger 250 GXTSmith Gas Axe
Reply:I am a machinist and a welder. I have held union jobs as each. As a welder, I worked at Motive Power building Locomotives. As a machinist, I worked at Nat'l Maint. and Repair. Both union shops and I worked them both for a year. Machinists are anal and welders are hammer guys. In the middle you find people who are like me. Welding should not be done in a lathe. That said, some things MUST be welded in a lathe. The trick is to take care in the process.NOW, we are talking about grounding the project. Never ground anything that is not the part. Never weld a part in a CNC, period. Sometimes you need to weld 100% the area you must maintain concentrically. How will you dial in a welded surface? Sometimes you can make a groove you can reference to, but you need two places if your parts is 3 dimensional.This part was easily removed and welded because it has multiple points of reference.This joker, on the other hand, only had a center drill point to reference.The care is given to respect the machinery by putting more protection than needed. Heat blankets, lots and lots and lots of heat blankets. Then a few more, for good measure, in all those stupid places dingle-berries go.In the shipyard, as a machinist, it would be common to call a welder over (union shop etiquette) and have him/her weld up a surface that was missed while the shaft was out and in their area. They just wrapped their ground wire around the shaft and tuck the clamp under the wire. They would always ground between the headstock and where the weld needed to go and not the other way around.My knowledge of this next bit is limited and my hypothesis is merely guesswork. I imagine that the electromagnetic field generated at the ground, with the wire wrapped around the shaft 3 or 4 times, works as a barrier to any wayward currents heading through it.I welcome anyone's thoughts on this.Bill LambertArgon WeldingABQ NMSic gorgiamus allos subjectatos nunc